Two former Parramatta Eels players are accused of harbouring semi-automatic weapons and possessing more than half-a-million dollars in cash after dramatic arrests in Sydney's Centennial Park yesterday.

West Australian Premier Colin Barnett says there is nothing to stop a mother trying to sue the government after her daughter apparently fell ill after a visit to bacteria-plagued Elizabeth Quay water park.

Five-year-old Chelsea Fawcett was hospitalised with an eye infection before doctors told her family she was partially blind in one eye and it was unknown if her sight would return to normal.

Slater and Gordon is investigating a claim on behalf of Chelsea against the state government.

Premier Colin Barnett said on Sunday he was sorry the child had an eye infection.

"I don't know that it's absolutely established it came from the water park but it may have," Mr Barnett told reporters.